What are invasive species?An invasive species is defined as an organism (plant, animal, fungus, or bacterium) that is introduced and has negative effects on our economy, our environment, or our health. Not all introduced species are invasive. The term “invasive” is reserved for the most aggressive species that reproduce rapidly and cause major changes to the areas where they become established.

Why are invasive species such a threat?Invasive species are a major threat to biodiversity on the planet. They are more than simply "species out of place"; these introduced species are far-reaching in their impacts, permanently altering landscapes and ecosystem functions. As native plant and animal communities are replaced by invasive species infestations, biodiversity declines and habitats change. The greatest impact is caused by introduced species that change an entire habitat, because many native species thrive only in a particular habitat.

While invasive plants are of serious concern in the Yukon, we have no known invasive animals. However, we do have introduced animal species that call Yukon home including Feral Horses, Feral Cats, House Mice, House Sparrows, Rock Pigeons, Three-spined Stickleback and Goldfish. There may also be introduced insect species here.

Invasive Plants
There are 154 introduced plant species in the Yukon. Only 20 are considered invasive. These unwanted invaders can negatively impact: rangelands by reducing forage quality and quantity; forestry operations by competing with seedlings for light, nutrients, and water; recreation opportunities by obstructing trails, and reducing aesthetics; and water quality and quantity by increased erosion and sedimentation.Control and management of invasive plants is expensive - the longer we wait the more expensive it will get.

Yukoners are in the enviable position of preventing plant infestations before they become so widespread that control is costly and eradication impossible.

How are invasive plants coming to the Yukon?Invasive plants are spread through several key pathways including increased travel and trade; transportation, horticulture, gardening, seed-mixtures (revegetation, birdfeed, wildflower mixes), recreation; and wildlife, livestock, humans, and pets.

Everybody can help:By knowing what species are considered invasive in the Yukon, you can detect new invaders and respond quickly and efficiently. On the following pages you can learn more about our most unwanted species and how to prevent their introduction, establishment and spread.